Well it's not a bug though. You must press Tab to lock the target in order to see the HP. Once you're out of range for target lock, it'll turn off and the pistol only works when you have a target locked.
That's weird. I mean it's hard to track the reason since the system is rather complex. Could you try to get out of the range and try to target lock again? I never got into such problem during hundreds of tests.
No matter what I did I couldn't get it to target lock again. I even tried leaving the room the boss is in and going back in and nothing. I'm not sure what caused it, I can't think of anything strange that I was doing when it happened.
yeah...let's just leave it there. What I want to know is if this problem consistently happening? I mean if it's happened everytime you play the game then there must be something which make it like that.